Electron-discharge device



Dec. 17, 1929. D. T. slMoNDs ELECTRON DISCHARGE DEVICE Filed July 20. 1925 on cl/s,

Patented Dee. 17, A192,9

UNITED STATES PATENT OFFICE Q DEWEYT. lBIIMONDS, 0F SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A COILBPORATION OF NEW YORK' ELECTRONDISCHABGE DEVICE Application :und Jury 2o,

My present \invention relates to electron discharge devices, and more particularly to devices of the four electrode type. The present application is directed to improvements over the devices of that type described and claimed in United States patent application, Serial No. 695,665,1iled by Albert W. Hull, March 3, 1924, and assigned to the same assignee as the present application.

It is well known that in the usual three electron discharge device there .is an appreciable capacity between the grid and anode, and that by reason of this capacity the amplifying eiiect of the device particularly at igh frequencies may be greatly reduced. This capacity-coupling also provides a feedback which tends to cause the production of self sustained oscillations in the circuits associated with the device. i

In order to overcome this diiiculty it has been .proposed to employ a fourth electrode known as a screening grid which is interposed between the control grid and the anode. By impressing a positive potential upon this screening' grid of a suitable value, the effects of capacity coupling between the control grid and the anode may be reduced. In order to entirely eliminate this capacity effect, however, precautions must be taken in the construction of the device to eliminate the eiect of capacity coupling between the current.

supply conductors to the electrodes as well as the capacity between the electrodes themselves.

The object of my invention is to provide an eiiicient structure for an electron discharge device whereby the effects of the capacity coupling between the electrodes and the leads which supply current to the electrodes may be entirely eliminated.

The novel features which I believe to be .characteristic of my invention are set forth with particularity in the appendedfclaims.` My invention itself, however, both as'to its organization and method of operation will best be understood by reference to the following description taken in connection with the accompanying drawing in which 1 is a cross sectional view of a device which may be used in carrying my invention into effect;

y19115. serial m. 44,654.

Fig. 2 is a cross sectional-view of a modi- `ficatlon; F1 3 1s a cross-sectional view taken of cylindrical form made up of ne wire wound round and secured to supporting rods has at its ends two metallic cylindrical members 6 and 7. Member 6 embraces a body of, "insulating material 8, which closes that end of the screenin grid, and member 7 surrounds and em races a reentrant tubular member 9, which forms a part of the receptacle 1. The screeninggrid is supported from the reentrant tubular member 7, being clamped thereto bya suitable clamp'lO. Current supply members 11 12, and 13 for the lscreening grid and cathode are sealed into reentrant tubular member 9. A second current supply conductor for the cathode passes -through the insulating` member 8 and is brought down to the base of the-tube and sealed therein at 14. The anode 3 is supported independently of the. other electrodes by means of springs 15 interposedbetween it and the wall of the receptacle 1. A current supply conductor 16 for the anode is sealed into the base of the receptacle at 17 and connected to the shell 18 of a Ll-contact base. F'or convenience of illustration this base has been shown with the contacts all in y line, lbut in practiceit will be preferable to have the contacts arranged in the usual manner. n n

To avoid the effect of capacity couplmg between the current supply conductor 12 for the control grid and the current supply conductor 16 for the anode, the metal shield 19 is provided. This shield extends into'the reentrant tubular member 9 and overlaps the cylindrical member 7 It is provided with a depending portion 20 which surrounds the *contacts 21. .Thisdepending portion 2 0 is anode. Circuit connections to the anode may be completed by means of a suitableconnection, not indicated, to thel socket shell27.

In the form of my invention shown in Fig. 2, reentrant tubular members 28 and 29 are provided at-both ends of the receptacle. The

screening grid 5is supported :from these two members in a manner -similarto that employed in the form of my invention shown in Fig. 1. The current supply conductor 30 for the anode is sealed into one end ofthe receptacle at 31 and the current supply conductor 32 for the screening grid is sealed into the same end of the receptacle at 33. Current supply conductor 34 for the control grid is sealed through the reentrant tubular member`28 and connected to a circuit connector 35, which may be secured to but insulated from a metal shell 36 adapted to enclose the entire device.

Sheldin members 37 and 38 embrace both ends of t e receptacle 1 and extendinto the reentrant tubular members 28v and 29 overlapping the cylindrical members 6 and'7,

which form the ends of the screening grid 5. The current supply conductor 39 for one end of the cathode 2 is connected to one of the base connections while the current supply conductor 40` to the other endof the cathode is conductively connected to the shielding-member 37. When the shell 36 is in the position shown, contact is establishedby means of the spring fingers 41 between the members 36 and 37 and thus a circuit is formed between the current supply conductor 40 and shell 42 of the base which is connected to one of the base contact members. In the operationof the device the shell 42 andthe screening members described will preferably be connected to ground and thus a grounded shielding system will be provided which will supplement the action of the screening grid and eliminate the effects of. all capacity coupling between the anode and control rid. Since circuit connection for the contro grid is established at the opposite end of the device from that of the anode capacity coupling between the external circuits 'of the two electrodes may readily be avoided.

While I have shown ad described two different modifications of my invention whereb v the desired results may be secured, it will, of course, be understood that many modifica4 tions in the structures employed may be made without departing from the scope of my invention as set forth in the appended claims.

What I claim as new and desire t-o secure by Letters Patent of the United States is 1. The combination in an electron discharge device of an evacuated receptacle of insulating material which encloses an electron emitting cathode, an anode, a control grid and a screening grid interposed between the anode and control grid, said screening grid having the form of a cylinder having its ends completely closed by members of insulating material, current supply conductors for the cathode and control grid which are sealed into said members of insulating material, a four contact base connected to one end of said receptacle, connections between the contacts on said base and supply conductors for the cathode, anode and screening grid, and means at the opposite end of said receptacle for establishing a circuit connection to the supply conductorfor the control grid.

2. The combination in an electron discharge device of an evacuated receptacle of insulating material which encloses an electron emitting cathode, an anode, a control grid and a screening grid interposed between` the anode and control grid, said screening grid having the form of a cylinder having its ends completely closed by members of insulating material, current supply conductor for the cathode and control grid which aresealed into said members of insulating material, a four Contact base connected to one end of said receptacle, connections between the contacts on said base and supply conductors for the cathode, anode and screening grid and means at the opposite end of said receptacle for establishing a circuit connection to the supply conductor for the control grid, said base comprisng a metallic shell through which connection may be established between one of the cathode supply conductors and one of the base contacts.

3. The combination in an electron discharge device of an evacuated receptacle of insulating material which encloses an electron emitting cathode, an anode, a control grid and a screening grid, interposed between the anode and the control grid and a'reentrant tubular member at each end of said rece tacle, said screening grid having the form o a cylinder whose ends are supported b and com pletely closed by said reentrant tu ular memers and metallic members which embrace the ends of said receptacle and extend into said reentrant tubular members.

4. The combination in an electron discharge device of an evacuated receptacle of insulating material. which encloses an electron emitting cathode, an anode, a control grid and a screening grid interposed between the anode and the control grid and a reentrant tubular member at each end of said receptacle, said screening grid having the form ot a cylinder whose ends are supported by and completely closed by said reentrant tubular members metallic members which embrace the ends of said receptacle and extend into said reentrant tubular members and a shielding. member which encloses said receptacle and which is conductively connected to said metallic members.

5. The. combination of an electron discharge device comprising an evacuated receptacleV of insulating material which encloses anzelectron emitting cathode, an anode, a control grid and a screening grid interposed between the anode and control grid and conductive meansfwithin the receptacle connected to the screening grid and mounted to act in conjunction with the screening grid to eliminate capacity coupling between the anode and control grid, and a conductive shielding member which surrounds said device and supplements the elli'ect of the screening system within the receptacle in eliminating undesirable capacity coupling.

6. The combination of an electron discharge device comprising an evacuated receptacle of insulating material which lencloses an electron emitting cathode, an anode, a control grid and a screening grid interposed between 4the anode and control grid and conductive means within the receptacle connected to the screening grid and' mounted toact in conjunction withthe screening grid to eliminate capacity couplin betwee the anode and control grid, a con uctive shielding member which surrounds said device and supplements the eiect of the screening system within the receptacle in eliminating undesirable capacity coupling, a current supply conductor for the control grid which extends through one end of said conductive shielding member and current supply conductors for the other electrodes which extend through the opposite end of said conductive shielding member.

7. The combination of an electron discharge device comprising an evacuated re ceptaclen-of insulating material which en closes anelectron emitting cathode, an anode, a control grid and a screening grid interposed between the anode and control grid and conductive means within the receptacle connected to the screening grid and mounted to act in conjunction with the lscreening grid to eliminate capacity coupling between the anode and control grid, a conductive shielding member which surrounds said device and supplements the effect ofthe screening system within the receptacle in eliminating undesirable capacity coupling,'and a contact on said conductive shielding member which co'- acts with a contact on the receptacle to complete a circuit connection to one of the electrodes.

8. The combination of an electron dis- .harge device comprising an evacuated receptacle of insulating material which encloses an electron emitting cathode, an anode,

a control grid and a screening grid interposed between the anode and control grid and conductive means within the receptacle connected to the screening. grid and mounted to act in conjunction with the screening grid to eliminate capacity coupling between the anode and control grid, a conductive shield- .lng member which surrounds said devlce and supplements the effect of the screening system within the receptacle in eliminating'un- 

